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Old 13-03-2009, 20:02   #1
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12volt or 6 volt

Can anyone offer advice on whether banks of 4 x 6 volt batteries are better than 2 x 12 volt for 12 volt house supply?
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Old 13-03-2009, 20:17   #2
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4X6 = batteries easier to carry but more connections to possibly fail
2X12 = heavier batteries but fewer potential connection problems
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Old 13-03-2009, 20:22   #3
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Better is a term that isn't really applicable. At face value there is no difference what so ever. There can be differences in any batteries both in terms of capacity and in terms of cost. Currently, I'm using 4 - 6 volts golf carts plus a 12 volt starting battery. In my last boat I used 2 - 12 volt AGM 4D's and a 12 volt starting battery. The difference was the charging system.

You have to match the charging system to the batteries in terms of type and by alternator. If you use one type of battery and fail to set the proper charging profile you are throwing money away. Batteries are a best planned as a total system. Every time you take amps out they have to go back - sometime.

Battery prices have actually doubled in the past 4 years. Who knows where they will go forward. Getting it right is more about cost these days. There isn't a brand or type that is best. It's when the whole system is planned out based on consumption and charging that you get the best system.

This is not like pick up trucks where you debate if the Chevy is better than the Ford.
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Old 13-03-2009, 20:46   #4
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Hey Paul, what size / design is your starting battery? I was considering a group 31 battery for my 100hp diesel...along with my 4 golfcart house bank.
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Old 13-03-2009, 21:11   #5
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Paul is right. Christain forget group size. That is only the physical dimensions of the battery. It has nothing to do with battery capacity. What you need to be concerned with is amp hours. You need to determine how many amp hours your on board equipment needs are (the Load) and then buy batteries that have about double the amp hours.
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Old 13-03-2009, 21:35   #6
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Hi Paul, Many thanks, I have got a handle on the basics but that about all! I recently added 2 x 130 amp Kyocera solar panels and have upgraded alternator from 55 to 80 amps. Biggest problem is that current house batteries are wet cell 150 amp x 2, 4 years old. I was thinking of upgrading to 4 x 6 volt Trojan L16H (420a/h @20a/h rate) As I understand things, this would give me a usable 402amp/hrs.

Cheers. Peter
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Old 13-03-2009, 22:55   #7
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Golf cart batteries are typically the cheapest per amp hour. Given their intended use, they are also the most robust batteries that are easy to find. Given the wide spread golf craze at almost every resort in the world, they are also easily found even in quite remote areas. The biggest thing about golf cart batteries is they aren't big. They aren't light but a hell of a lot easier to carry and move around than a comparable 2
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Old 13-03-2009, 22:59   #8
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I just want to touch on that not all brands are created equal. I have found the quality of the brand, "American Battery" to be superior to the other brands offered by the chain marine businesses (you know who I mean). There of course is a limit to cost vs. the time they last. I hear Rolls batteries are very expensive and very high in quality.
Christian...To answer your question about a cranking battery. If you have the space, cram the largest one in you can. More is better...at least that's what my ex-wife told me at our divorce proceeding's!
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Old 14-03-2009, 07:13   #9
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Quote:
Originally Posted by roverhi View Post
Golf cart batteries are typically the cheapest per amp hour. Given their intended use, they are also the most robust batteries that are easy to find. Given the wide spread golf craze at almost every resort in the world, they are also easily found even in quite remote areas. The biggest thing about golf cart batteries is they aren't big. They aren't light but a hell of a lot easier to carry and move around than a comparable 2
I second the golf cart battery.
Trojan is the best. Brand does matter in the studies I have read. Rolls are the best, but the most expensive.
You get what you pay for. Most agree that the trojan brand is a great battery. The T105 gives you 220ah @ 6v. Price right now seems to be around 160-220 USD here in Texas. You could get a battery cheaper, but will it last ?

For me, a do it yourselfer, I would rather lug a 65LB battery, than a 130 lb battery. The connection problem is really not a issue, just a bit more expense initally. Keep them clean, charged, equalized and ventilated and dry, should be no problem.

Some real promising technology coming down the road soon for batteries. But as with most things, early adopters will pay more.

Flooded wet cells can last a long time with proper care. The price to ah point seems to be the best, and they are available.

Bob
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Old 14-03-2009, 09:40   #10
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the tecnical page on the trogen web site says that they are designed to be cycled down to 80% so that gives you a much better weight/£ per usable amp reatio.
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Old 14-03-2009, 11:48   #11
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Philip; that is a little misleading. Read this document.

Trojan Battery Company

Quote:
1. Shallow discharges will result in a longer battery life.

2. 50% (or less) discharges are recommended.

3. 80% discharge is the maximum safe discharge.
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Old 14-03-2009, 11:52   #12
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Philip; that is a little misleading. Read this document.

Trojan Battery Company

they dont say how much longer they last if you go 50%
so there normal rated life is calculated on 80% use!
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Old 14-03-2009, 11:57   #13
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Not so. Did you read the document that I linked to? Or the first three items from that document that I posted?

I think you will find that the "normal rated life" is calculated on about a 30% discharge.
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Old 14-03-2009, 12:01   #14
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4. Do not fully discharge flooded batteries (80% or more). This will damage (or kill) the battery.

5. Many experts recommend operating batteries only between the 50% to 85% of full charge range. A periodic equalization charge is a must when using this practice.
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Old 14-03-2009, 12:03   #15
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Don't confuse "80% of full charge range" with "80% discharge". They are opposites.
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